A strong desire for increased automation in the workplace, and a desire to increase the use of animated figures depicting animals, humans or other characters in entertainment and other situations, along with an increased ability to control such mechanical manipulators has led to substantial efforts in the development of robotics. As a result, significant advances have occurred in many aspects of robotics.
Perhaps the most widely used controlled component in robotic systems is a mechanical manipulator, that portion of a robot used to change the position of orientation of selected objects engaged by that manipulator. In many instances, such mechanical manipulators are desired to have capabilities similar to those of the human wrist or shoulder, that is, exhibiting two (or in some instances, more) degrees of freedom of motion.
Although a number of such mechanical manipulators have been developed which to a greater or lesser degree achieve some of these desires therefor, most have been relatively complicated devices requiring complicated components and difficult assembly procedures or both. Many, in addition, represent compromises in having relatively limited range, or singularities within the ranges, or other limitations in performance. Thus, there is a strong desire for a mechanical manipulator which can, under control of the user, position objects anywhere over at least a hemispherical surface without any singularities in the operation of the device in this range, and which can be made both reliably and inexpensively.
One such mechanical manipulator meeting this desire comprises a base support, a pivot holder and a plurality of pivoting links. The pivoting links are rotatably coupled to both the base support so as to be arrayed by rotational axis radially thereabout and to members of the pivot holder to rotate about axes which extend in different directions for each of these rotatable couplings in a link typically in accord with specific geometrical arrangements, and in different directions from similar axes in another of such links. The pivot holder is linked with a second plurality of pivoting links to a manipulable support. Such systems can incorporate a variety of force imparting members to control movements of various ones of the pivoting links or pivot holder members with as few as two being required. Pivot holder members having hinged portions with one portion rotatably connected to a first plurality pivoting link and the other portion rotatably connected to a second plurality pivoting link provides a capability for controlling the separation between the base and manipulable supports, but requires an actuator for each first plurality pivoting link and has its manipulable support positioned less precisely.
Another manipulable support meeting this desire comprises a base support, a pivot holder with hinged members and three pivoting links. The pivoting links are rotatably coupled to both the base support, but this time to be arrayed by axis more or less tangentially thereabout, and to members of the pivot holder to rotate about axes which extend in different directions for each of these rotatable couplings in a link typically in accord with specific geometrical arrangements, and in different directions from similar axes in another of such links. The pivot holder is linked with another three pivoting links to a manipulable support. Such systems can incorporate a variety of force imparting members to control movements of various ones of the pivoting links or pivot holder members with three being required.
This latter mechanical manipulator has a stronger construction than the former in having the three pivoting links connected to the base support with the rotation axis for each positioned tangentially thereto rather than being more or less cantilevered radially therefrom. However, there is much less vertical support provided to loads on the manipulable support positioned at relatively extreme angles with respect to vertical in some radial positions. Furthermore, many of the piece parts must have surfaces that are other than perpendicular or parallel to one another requiring much expensive odd angle machining. In operation, the operation of any one actuator can not be controlled independently from the others because of the unavoidable coupling between the three pivoting links making control considerably more difficult. Thus, there is a desire for a mechanical manipulator that is economical, strongly constructed and capable of providing relatively good vertical support for output loads even at extreme angular positions.
The present invention provides a controlled relative motion system comprising a base support, a manipulable support, a group of link end constrainers each having a first portion movably connected to a second portion thereof so that ends of the first and second portions can be selectively separated from one another in a selected direction so as to have a selected distance therebetween, and two groups of pivoting links. With at least four link end constrainers in the group thereof, the first group of pivoting links has at least four links therein each rotatably coupled to a force imparting means or to the base support so as to be rotatable about a corresponding base link axis where each of said base link axes extend into regions between adjacent ones of the first group of pivoting links into which regions said base link axes of said adjacent ones also extend, or both, and each coupled to a first portion end of a corresponding one of the group of link end constrainers. The second group of pivoting links has at least four links therein each rotatably coupled to the manipulable support so as to be rotatable about a corresponding support link axis and each coupled to the second portion end of a corresponding one of the group of link end constrainers. Various kinds of force imparting members can be used connected to the first group of pivoting links to position the manipulable support both in rotation and in translation as desired. These force imparting devices may be eliminated to provide a constant velocity rotatable, bendable joint, or they may be replaced by shock absorbers to provide an impact management device.
Four or more, or less, in number of link end constrainers in the group thereof are useable in the form of straps or interconnected xe2x80x9ceyexe2x80x9d bolts. A strand, often in the form of a cable, extending through the base and manipulable supports can be used to operate or position devices on or adjacent to the manipulable support through rotating or translating the strand, or through translating or rotating the manipulable support, or some combination thereof.